Mounting clip for pot core



, 1955 A. c. STURGIS MOUNTING CLIP FOR POT CORE July 27 Filed April 1,1965 FIG? INVENTOR ANDREW C. STURGIS,

HIS ATTORNEY.

United States Patent 3,l7,167 MUUNTHNG CLllP 1 8T Cti llll Andrew C. Sturgis, llynchburg, Vac, assignor to General Electric Company, acorporation of New York Filed Apr. 1, 1963, Ser. No. 269,584 3 Gaines.(til. 243-314) This invention relates to fastening devices for securinga plurality of electrical components in a fixed spatial relationship.More particularly, the invention relates to a mounting clip for firmlysecuring a plurality of ferrite core members.

High fre uency inductive devices such as pulse transformers, filterinductances, etc, frequently utilize magetic core members formed offerrite materials. Ferrites, which are oxides of various ferrouselements, are characterized by high permeability and high resistivity,thereby permitting efficient operation while yet minimizing eddy currentlosses. Ferrite magnetic cores are often fabricated as semi-cylindricalcup-like elements which include a center leg or projection. Two of thesecup-core members are assembled to form the magnetic core, with thecenter legs forming an air gap which controls the reluctance of themagnetic circuit. One or more coils surrounds these center legs orprojections and are customarily mounted on a nonmagnetic bobbin fittinginside of the annular space formed by the cup-core halves and theircenter projections or legs. It is immediately apparent that theinductance of the device is controlled to a substantial degree by thereluctance of the magnetic circuit which, in turn, is determined by thedimensions of the air gap formed by the center legs of the cup cores.Hence, it is quite important that the individual cup-core halves formingthe core of the inductor be ri idly and fixedly mounted in order tomaintain the proper air gap, and to prevent relative rotational movementof the cupcore halves.

it is, therefore, a primary object of this invention to provide amounting means for a ferrite cup core inductive device in which the cupcore members are firmly and rigidly maintained in a desired abuttingrelationship.

In the past, it has been customary to assemble the cup cores in thedesired fixed spatial relationship while simultaneously mounting them ona chassis or printed wiring board by means of a clip or other fasteningmeans. The fastening means exerts force on the cup cores during theassembling process and brings them into an abutting relationship. Thisarrangement for assembling the cup cores of the inductive devices leavesmuch to be desired. The position of the cup cores, and the clampingpressure with which they are held, thus depends on the skill of theoperator in tightening the clip properly while mounting the device. Toooften, unfortunately, this skill is not present, and consistent esultsare difficult to obtain on a mass pr duction basis. Since the inductanceof the device is a function of the air gap and this in turn depends uponthe manner in which the cup-core halves are assembled, a great deal ofdifficulty has been encountered in obtaining consistently good inductivedevices at a reasonable cost.

Furthermore, if any of the units fail to meet test specifications,whether due to errors introduced by the assembly procedure itself orotherwise, the initial dirliculty is further compounded becausedisassembly and reassembly of these units again depends on theassemblers skill, takes a good deal of time, and is generally a complexprocedure. In fact, it is often simpler and less expensive to discard anentire core-coil assembly rather than attempting to rework or correctthese errors. Similarly, if a core-coil assembly deteriorates duringoperation, the problem of disassembling and reassembling the coreelements in order "ice to repair them is also sufficiently troublesomethat it is often simpler and less expensive to scrap the entire corecoilassembly. In any event, the excessive assembly time, high scrap andrework average all add to the manufacturing cost and the price of thedevice. Hence, a need exists for a mounting clip assembly for ferritepot core inductive devices wherein the pot cores are firmly,effectively, and simply assembled prior to attachment of the entiredevice to the chassis or printed wiring board.

It is, therefore, a further object of this invention to provide a cupcore mounting clip wherein the cup cores are firmly fastened to maintaina constant air gap without depending upon the skill of an operator toachieve the results;

Still another object of this invention is to provide a mounting clip fora cup-core assembly wherein the cup cores are firmly fastened togetherbefore attachment of the entire assembly to the supporting mediums;

Yet a further object of this invention is to provide a mounting clip fora cup-core assembly in which constant and consistent results areachieved in terms of the mounting pressure of the cup-core members andthe air gap of the magnetic core assembly.

in addition to maintaining the proper air gap by applying a constant andfixed pressure to the cup-core halves, rotational movement between thetwo cup-core halves must be avoided in order to prevent any distortionof the flux path through the core members. In prior artmountingassemblies, it was quite common for the two cup-core members tobe rotated relative to each other either during the assembly operationitself or later due to vibratory conditions to which the inductancedevice was subjected.

Hence, yet another object of this invention is to provide a mountingclip for a cup core inductive assembly wherein rotational movementbetween the cup-core halves is positively prevented;

A still further object of this invention is to provide a mounting clipfor a cup-core inductive assembly wherein the cupcore assembly isinsensitive to vibration.

ther advantages of the instant invention will become apparent as thedescription thereof proceeds.

In carrying out the various objects of the invention, a cup-coremounting clip is provided which has a deformable, arcuate bottom, tworesilient side members or legs and a pair of flanges extending laterallyfrom the side members. The cup cores are p essed against the arcuatebottom causing it to flatten out and snapping the flanged member overthe top of the cup core thereby exerting positive and constant pressureon the two cup cores and preventing reiative rotational movement. Afterthe cup-core halves have been thus assembled in the mounting clip, themounting clip may be fastened by any suitable means to the chassis orprinted wiring board which represents the supporting member for theinductance device.

The various features of this invention, which are believed to be new andnovel, are set forth with particularity in the appended claims. Theinvention itself, however, may best be understood by reference to thefollowing description when taken in conjunction with the accompanyingdrawing in which:

PEG. 1 is a perspective showing of the cup cores in an assembledposition;

FIG. 2 is an exploded view of the assembly of FF. 1 showing the twocup-core halves and the mounting clip;

FIGS. 38 are schematic diagrams illustrating the mannor in which the cupcores are assembled in the clip and are useful in understanding thefunctioning of the clip.

FIG. 1 is a perspective showing of the cup cores secured in the novelmounting clip and the entire assembly ready to be fastened to a chassisor printed wiring board. The

a orns? v.23 assembly consists of two cup-core halves 2 and 3 mounted ina clip shown generally at l. The cores are firmly clamped in an abuttingrelationship by flanges 4 and 5 i which extend laterally from tworesilient side members 6 and 7, attached to a resilient, deformable,arcuate bottom member, not shown in FIG. 1. Two mounting tabs 9 and arethe means by which the entire assembly may be fastened to the chassis orprinted wiring board. The mounting tabs Q and to contain suitablethreaded screw holes 1i and 12 through which a fastening means is passedand attached to the mounting surface.

Cup cores 2 and 3, as may be seen most clearly in PEG. 2, are generallycup shaped and include center legs or projections l3 and 1d. The centerlegs, together with the side walls of the cup core, form an annularspace to in which a non-metallic bobbin supporting one or more coils,not shown, is positioned. The non-magnetic bobbin and its associatedcoils surround the center legs 13 and 14 of the cup cores. The height ofcenter legs 13 and is is less than the height of the core walls so thatin the assembled position an air gap 15 is formed, which air gapcontrols the reluctance of the magnetic circuit formed by cup cores 2and 3. Axial passages 17 are provided in the cores and are adapted toreceive a small ferrite plunger 18 which is utilized as an adjustingdevice for the coil. The upper edges 1? of the cup-core wall arecustomarily machined to close tolerances so that a very tight fit isobtained when the two cup-core halves are pressed into abutting rel. onship by the mounting clip. A plurality of openings provide a means forbringing the various coil leads into and out of the assembled cup core.t will be appreciated that because of these openings in the cup core thedevice is position sensitive since any relative rotation of the cupcorehalves, which disturbs the alignment of openings 20, distorts the fluxpath through the outer walls of the cup core. As pointed out previously,in addition to the need for firm seating of the cup-core halves so thatthe proper air gap is maintained, the mounting clip must preventrelative rotational movement of the cup-core halves in order to avoiddistortion of the flux path through the core.

The mounting clip l is constructed to achieve this desired result. Asseen in PEG. 2, the mounting clip includes two resilient members or legs6 and '7' which are shaped to conform to the cylindrical shape of thecore. These legs extend from a deformable arcuate bottom member 21 whichis flattened in assembly to firmly secure the cores. The arcuate bottommember 21 has a central cutout portion 22 for reducing the weight of theentire device and to permit adjustment of tuning slug ill") from thebottom side. The arcuate bottom 21 and flanges and 5 firmly secure thetwo cup-core halves in an abutting relationship. The arcuate member 211is flattened dur ing assembly until flange members 4 and 5 snap overhcup cores thus maintaining them firmly under axial pressure andpreventing rotational movement.

In the normal unflexed position the distance from the crown of thearcuate bottom member 21 to the top of the flange members 4 and 5 isless than the height of the as sembled cup cores 2 and 3. In order toassemble the two cup cores, the deformable, arcuate bottom member isfiattened until flange members 4 and 5 snap over the top of the cupcores thereby firmly holding the two cup-core members in an abuttingrelationship. it will be apparent from observation of the mounting clipof PKG. 2 that deformation or flattening of the arcuate bottom member 2by the cup-core members produces an upward force against the bottomcup-core member along the axis of the core which is in contact withbottom member Similarly, it will be appreciated that the flange membersand 5 produce a downward force against the top cup core at right anglesto the force exerted by bottom 21, and that the force thus exerted bythe bottom member 2.1 and flanges d and 5' maintains the two cup-coremembers in a firm abutting relationship.

Inasmuch as the force due to the deformed, resilient bottom member isalong one axis and the force due to flange members and 5 is at rightangles thereto, the pressure exerted on the two cup-core members isevenly distrib d around edges of the cup core insuring proper seathg ofthe members along the entire circumferonce.

The manner in which the cup cores are mounted in the novel mounting clipand the manner in which the mounting is achieved may be most easilyunderstood by reference to FEGS. 3-8 which are schematic diagramsillustrating the mounting clip at various stages dunng the assemblyprocess. Thus, PEG. 3 illustrates the two cup-core halves 2 and 3, shownin phantom, prior to their insertion in mounting clip l which is then inthe unliexed position.

To insert cores 2 or 3 the two cup cores are placed together and theside me ers d and T of mount' clip 3. are

forced apart either by the ho ors or any suitable assembly tool and thecup cores partially inserted therein as illustrated in EEG. 4.

The cup cores 2 and 3 are pushed into the mounting clip until the bottomcup-core half rests against the crown of arcuate bottom member 21 of theclip. As may be seen in PEG. 5, cup core 3 makes tangential contact withthe bottom member 21 along an axis extending into the plane of thepaper. The total height of cup cores 2 and 3 is greater than the heightof the clip from the crown of the arcuate member to tile flange 5 and 6so that the ges do not extend over the cup core members. As pressure isexerted on the cup cores, a pressure shown by means of the arrow 24 ofFIG. 6, bottom member .21 is partially lattened, and the flanges f5 and6 move upward along the side wall until, as shown in FIG. 7, the bottomis flattended sufficiently for flanges d and 5 extend over the upperedge of the cup-core members. A slight additional increment of pressureon the cup cores flattens the bottom sutliciently for flanges i and 5 tosnap over the top of the cup-core members into the final assembledposition.

While a particular embodiment of the invention has been described andshown, it will, or" course, be understood that it is not limited theretosince many modifications and variations in the method and the circuitarrange ment for pairing out the invention may be made. it iscontemplated that the appended claims cover any such modifications asforward in the true spirit and scope of this invention.

What is claimed and desired to be secured by Letters Patent of theUnited States is:

1. In a clip assembly for fixedly retaining two cylindrical cup-corehalves in abutting relationship the combination comprising a deformablebase having a substantially arcuate shape, a pair of resilient curvedside members extending vertically from said base, said side members andsaid base deining a generally cylindrical space for receiving both ofthe cup-core halves in their entirety, coplanar flange members extendinglaterally from said side members, said flanges and said base cooperatingto exert axial pressure on said cup-core halves to retain them inabutting relationship and to prevent relative rotation of the halves,the distance from the crown of said arcuate base in the undeformed stateto said flange designed to be less than the height of the two cup-corehalves whereby said flange members extend completely over said cup-corehalves to exert pressure on the cup-core halves only who said base isdeformed.

2. in a clip assembly for retaining two position sensitive magneticelements in a fixed abutting relationship, the combination comprising aresilient base, bowed along one axis, a pair of resilient side membersconformed to the shape of the elements to be retained extending fromsaid base in a general parallel direction with said axis to define aspace for completely receiving the elements to be retained andpreventing relative movement therebetween, coplanar ilange membersextending aterally from said side members for evenly distributing tiepressure around the elements to be retained, the distance between thebow of said base in the undeformed state and said flange membersdesigned to be less than the total height of the magnetic elementsthereby retained whereby said flange members snap completely over saidelements in the assembled state to retain said members under pressure.

3. In a clip assembly, for retaining two cylindrical magnetic elementsin a fixed abutting relationship, the combination comprising a generallycircular, arcuate deform able base having a bow along one diameter ofthe circular base, a pair of arcuate resilient side members conformingto the cylindrical shape of the elements to be retained extending fromsaid base generally in parallel to said bow to define a cylindricalspace for completely receiving the elements to be retained andpreventing relative movement therebetween, arcuate coplanar flangemembers extending laterally from said side members for exerting pressureon said members generally at right angles to that ex- References Citedby the Examiner UNITED STATES PATENTS 2,225,592 12/40 MacFadden 248--3612,230,923 2/41 Barry 248-309 2,539,581 1/51 Holden 248361 2,541,828 2/51Peck 248-300 CLAUDE A. LE ROY, Primary Examiner.

FRANK L. ABBOTT, Examiner.

1. IN A CLIP ASSEMBLY FOR FIXEDLY RETAINING TWO CYLINDRICAL CUP-COREHALVES IN ABUTTING RELATIONSHIP THE COMBINATION COMPRISING A DEFORMABLEBASE HAVING A SUBSTANTIALLY ARCUATE SHAPE, A PAIR OF RESILIENT CURVEDSIDE MEMBERS EXTENDING VERTICALLY FROM SAID BASE, SAID SAIDE MEMBERS ANDSAID BASE DEFINING A GENERALLY CYLINDRICAL SPACE FOR RECEIVING BOTH OFTHE CUP-CORE HALVES IN THEIR ENTIRETY, COPLANAR FLANGE MEMBERS EXTENDINGLATERALLY FROM SAID SIDE MEMBERS, SAID FLANGES AND SAID BASE COOPERATINGTO EXERT AXIAL PRESSURE ON SAID CUP-CORE HALVES TO RETAIN THEM INABUTTING RELATIONSHIP AND TO PRECENT RELATIVE ROTATION OF THE HALVES,THE DISTANCE FROM THE CROWN OF SAID ARCUATE BASE IN THE UNDERFORMEDSTATE TO SAID FLANGE DESIGNED TO BE LESS THAN THE HEIGHT OF THE TWOCUP-CORE HALVES WHEREBY SAID FLANGE MEMBERS EXTEND COMPLETELY OVER SAIDCUP-CORE HALVES TO EXERT PRESSURE ON THE CUP-CORE HALVES ONLY WHEN SAIDBASE IS DEFORMED.